Systematic Assessment of New Snow Settlement in Snowpack
Systematic Assessment of New Snow Settlement in Snowpack
复制标题
积雪中新雪沉降的系统评估
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
F. Obleitner
中科院分区：
文献类型：
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作者：
W. Steinkogler;C. Fierz;M. Lehning;F. Obleitner
在降雪后的最初几个小时和几天内，新的积雪沉降尚未完全了解。这一初始阶段的建模误差会在整个冬季传播，从而影响对关键积雪特性（如密度、温度分布和雪深）的正确建模。到目前为止，在SNOWPACK中，沉降参数的调整主要是通过将模拟沉降曲线与实测沉降曲线进行视觉比较来完成的。这可以通过跟踪与沉降和温度传感器（雪竖琴）相对应的模型层来完成。因此，用现场测量验证模型性能是可能的。此外，使用这样一个竖琴作为下边界条件，可以在不考虑早期模拟误差的情况下分析该竖琴上方的积雪演变。这里使用了在多个降雪期间获得的综合数据集。除了雪竖琴数据外，降雪后几天拍摄的高分辨率密度剖面为模拟的积雪演变提供了进一步的验证。基于这些观测结果，我们提出了一种系统的方法来评估模型在降雪期间和降雪后几天的性能。敏感性研究可以确定影响新积雪沉降的最重要的模型参数。更详细地研究了类型（晶粒和键大小）和状态变量（温度）的具体影响。因此，提出了一种新的温度参数化方法。这被证明对加强单次降雪事件的调查是有价值的，而长期积雪沉降模拟的重大改进仍有待完成。
New snow settlement in the very first hours and days after a snowfall has not yet been fully understood. Modelling errors at this initial stage propagate through a whole winter season, thus affecting a correct modelling of crucial snow cover properties such as density, temperature distribution and snow depth. Up to now, parameter tuning for settling in SNOWPACK has mainly been done by visual comparison of modelled with measured settling curves. This can be accomplished by tracking model layers that correspond to positions of combined settlement and temperature sensors (snow harps). As a result, verification of model performance with in situ measurements is possible. Furthermore, using such a harp as a lower boundary condition, snow-cover evolution above this harp can be analysed irrespective of earlier simulation errors. Here comprehensive data sets obtained during a number of snowfall periods are used. In addition to snow harp data, high resolution density profiles taken in the days following a snowfall provide for further verification of the simulated snow-cover evolution. Based on these observations we present a systematic approach to assess the performance of the model both during and a few days after snowfalls. Sensitivity studies allow to locate the most important model parameters which influence the settlement of freshly deposited snow. The specific influence of both type (grain and bond sizes) and state variables (temperature) was investigated in more detail. As a consequence, a new temperature parameterisation is suggested. This proved valuable for enhanced investigation of single snowfall events, while a significant improvement of long-term simulations of snow settling is still pending.